Dashboard Regions Weather Stations Radar Alerts Glossary
Contact About
Log In

Register for an account and never miss a forecast again!

Register

Avalanche Forecast

Archived

Jan 11th, 2023–Jan 12th, 2023

Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural and human triggered avalanches likely.
Treeline
Natural and human triggered avalanches likely.
Below Treeline
Natural avalanches unlikely, human triggered possible.

Regions

Banff Yoho Kootenay, Banff, East Side 93N, Kootenay, Lake Louise, LLSA, Sunshine, West Side 93N.

The weather is changing and so is the avalanche danger. An Atmospheric River over BC and AB will deliver strong winds, warming and up to 20 cm of snow (rain in the valley) = chinook conditions on the east slope and pounding snow and rain to the west. Avalanche danger rises on Thursday, again on Friday and peaks on Saturday. Expect windslab development and a reawakening of the deep persistent problem.

Confidence

Moderate

Avalanche Summary

The sun was out! Two natural avalanches reported on S aspects on Wednesday: Mt. Ball S face had a size 3 natural (observed from a distance) and Bourgeau Left-hand waterfall released a size 2 natural that started up high in the rocks. Minimal results from avalanche control at the ski areas. No new avalanches observed by our field team on the Ogden Bench.

Snowpack Summary

10-20 cm of loose snow sits over a denser mid-pack which has formed a slab over the weak facet layers below - this loose snow will get blown into windslabs starting Thursday. The December 17 weak layer is down 25-60 cm and becoming less reactive. The November 16 deep persistent layer of facets and depth hoar is near the base of the snowpack, continuing to show sudden failures. Puzzle Peak snow profile from Tuesday.

Weather Summary

The weather pattern is changing as an Atmospheric River establishes itself across southern BC and AB. The coast and interior ranges will see heavy rain, snow, wind and warming. Here in the Rockies, we expect the winds to start on Thursday and reach 80 km/hr by Friday. Some snow and perhaps rain at low elevations with 5-10 cm by Friday. Expect warm and windy weather!

Terrain and Travel Advice

  • Uncertainty is best managed through conservative terrain choices at this time.
  • Use careful route-finding and stick to moderate slope angles with low consequences.

Problems

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

Deep Persistent Slabs

Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.